Cars are less careful around riders wearing helmets. source
The second:
A helmet effectively makes your head larger, and as such increases the risk of your head hitting the road. In fact your risk doubles. source
A helmet protects against ‘focal’ injuries, that is injuries at the point where your head hits something. But a another type of brain injury is ‘diffuse’ injury, basically the fact your head hit something at all, and your brain rattles around in the skull. This type may cause worse problems than focal injuries. The added size of the helmet amplifies the rotation of your head on impact and makes this type of injury worse. source. Add to this the fact that wearing a helmet makes you more likely to hit your head in the first place.
In addition to this, wearing a bicycle helmet makes cycling less attractive, and as a result people will cycle less. This results in a loss of health benefits from cycling.
Sure, intuitively you might think a helmet will make you safer, but intuition is often wrong. When you look at the actual data it shows a different picture.
It seems like this is not yet settled. This meta-analysis of studies concerning increased risk-taking found that most studies with experimental data did not find that wearing a helmet increased risk-taking behavior. The author mentions the downhill biking experiment and suggests that there’s a distinction between taking more risks because you are wearing helmet and riding slower because you feel unsafe without one. This is supported by the habitual non-wearers not increasing their speed/risk when wearing a helmet.
This Other analysis looks at the actual rates of different kinds of injuries and finds that helmets significantly decrease the risk of head and face injuries while not having a significant impact on neck injuries.
This study of hospital stays related to bike accidents shows that hospital stays were significantly more frequent and severe for those who didn’t wear helmets. (and it examines some of the potential cultural hurdles in expanding helmet use).
Overall, I’m most influenced by the last study. Theoretical analysis of risk taking and injury type is certainly important, but the real life data in this and other studies indicates that wearing a helmet strongly correlates with a decreased risk of injury and death.
Because wearing a helmet makes you more likely to be in an accident and increases the risk of brain injury when you are.
The first has two causes:
The second:
In addition to this, wearing a bicycle helmet makes cycling less attractive, and as a result people will cycle less. This results in a loss of health benefits from cycling.
Sure, intuitively you might think a helmet will make you safer, but intuition is often wrong. When you look at the actual data it shows a different picture.
It seems like this is not yet settled. This meta-analysis of studies concerning increased risk-taking found that most studies with experimental data did not find that wearing a helmet increased risk-taking behavior. The author mentions the downhill biking experiment and suggests that there’s a distinction between taking more risks because you are wearing helmet and riding slower because you feel unsafe without one. This is supported by the habitual non-wearers not increasing their speed/risk when wearing a helmet.
This Other analysis looks at the actual rates of different kinds of injuries and finds that helmets significantly decrease the risk of head and face injuries while not having a significant impact on neck injuries.
This study of hospital stays related to bike accidents shows that hospital stays were significantly more frequent and severe for those who didn’t wear helmets. (and it examines some of the potential cultural hurdles in expanding helmet use).
Overall, I’m most influenced by the last study. Theoretical analysis of risk taking and injury type is certainly important, but the real life data in this and other studies indicates that wearing a helmet strongly correlates with a decreased risk of injury and death.